Current-wave transmission



Feb. 23 1926. 1,573,954

' H. J. VENNES CURRENT WAVE TRANSMI S S ION Original Filed y 26, 1919 Patented Feb. 23, 1926.

UNITED STATES PATENT OFFICE.

HARALD J. VENNES, OF MONTREAL, QUEBEC, CANADA, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED; OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Application filed May 26, 1919, Serial No. 299,749. Renewed April 15, 1925.

To all whom it may concern:

Be it known that I, HARALD J. VENNES, a citizen of the United States, residing at Montreal, in the Province of Quebec, Dominion of Canada, have invented certain new and useful Improvements in Current- Wave Transmission, ofwhich the following is a full, clear, concise, and exact description.

This invention relates to transmission of currents of different frequencies, and more particularly to any system in which currents of diiferent frequencies are to be impressed at the same' time independently upon the same circuit, such as, for instance, in multiplex signaling. The invention comprises a simplified circuitarrangement for associating a number of different current sources with a common line whereby currents having different characteristics are conveyed from said sources to said line without interference and in an efficient manner.

Heretofore, for example, as indicated in U. 8. Patents No. 1,313,433 to,R. A. Heisissued August 19, 1919, and No. B. W. Kendall, issued February 13, 1923, it has been the practice to connect current generators pf d iferent frequency to a common line through an amplifier for each such generator and a selective circuit between each amplifier and the line. This necessitates the use of as many amplifiers as there are generators and means that each selective circuit must carry the amplifiedcurrent, and each amplifier mustprovide for the losses inthe selective circuit due to the amplified currents.

According to the invention one amplifier suflices for all the generators and th s results in considerable saving of amplifiers, especiallyin systems carrying, for example,

or transmissions in each direction.

ing, 1,445,141 to Also in the system according to the invention the selective circuits carry the generated butnot the amplified currents, so that the lossesincurred in these portions of the circuit are considerably reduced. In the drawing, line 1 may be a multiplex transmission line upon which currents of difier'ent frequencies are to be impressed from a series of generators of which 0 and O are shown. By the conjugate arrangement' comprising line coils 2 and 3 and the line balance 4, as shown, the line may be adapted for two-way transmission of currents, so that incoming currents may be received by suitable receivers of which one, indicated B, is shown.

The generators such as 0 and 0 may be of any suitable type for producing oscillations of the desired frequencies. Each of the ones shown is of the thermionic type having an oscillatory input circuit 5 into which energy is fed from the output circuit .by means of mutual inductance between the input and output circuits. The space-current circuit for the oscillator from the source 6 includes a normally open contact 7 which may be controlled by a relay 8 in the circuit of which a key 9 is shown, so that with key 9 closed the space-current is supplied to the oscillator and sustained ozcillations of definite frequency are set up in the oscillatory or filtering circuit 10 to WhlCll coil 11 in the output circuit of generator O is coupled. Generator 0 by a similar coil 12 delivers current to tuned or filtering circuit 13 of a different frequency from the current produced in circuit 10 by generator 0,. Oscillatory circuits 10 and 13 are tuned to their respective generator frequencies which as stated are different so that energy from generator 0,, for example, produces maximum 'oscillations in circuit 10 but has negligible effect on oscillatory circuit 13. By this provision the output energy of either generator is prevented from reacting upon the other and current of each frequency is imprexed across the terminals of resistance 14. This resistance acts as a potentiometer along which the taps 15, 16 may be adjusted to regulate the voltage impressed upon the respective grids of amp-lifier 17. It is the function of amplifier 17 to amplify non-selectively all the currents impressed upon it. An amplifier capable of handling currents of considerable frequency range is necemary for this purpose, and it must possess a substantially linear characteristic throughout the operating range so that currents of the difierent frequencies shall not modulate one-v another. The particular t pe shown is that in which two discharge evices 1'8 and 19 are so associated that a given impressed potential across the input resistance 14 causes at any instant, equal and opposite variations in the grid potential of the respective grids of the two discharge devices, and is known as the no push-pull type. As a result of the complemental impedance variations thus caused in 'the two dischargecdevices, amplified current flows in the output coil 20 and is impressed 5 through coil 21 upon the line 1'.

Incoming currents in line 1 produce current flow through coils 22 to the input of the two-stage amplifier A A which is also adapted to pass currents of considerable frequency range without interference between the currents of different frequencies, and each stage of which may be of the same general type as amplifier 17. By means of the conjugate arrangement for connecting to the line 1, currents from amby relay 26, which may control a local circuit as indicated or if desired a telephone receiver or other suitable receiver may be used.

While the particular generators, transmitters andreceivers illustrated and described are for telegraph transmissiomit isobviousthat the invention is adaptable.

generally to transmission of currents of dif- I ferent frequencies for the selective operation of any desired mechanism, an example being-carrier currents, which may be modulated in accordance with any desired kind of signal, for instance',las by speech by pro? viding' the approprlate kind of transmitter and receiver, such, for instance, as amicrophone and a telephone receiver. It is obvious also that transmitting and receiving antennae may be substituted for the line.

While the invention has been illustrated and described with reference to a particular system it is to be understood that it is not to be limited either to the specific system or circuit arrangements as a whole, or to the particular details, but only by the scope of the appended claims.

What is claimed is:- 1. In a system of current transmission, a line for 'simultaneouslybonveying currents of different frequencies a plurality of means for producing currents of different frequencies for said line, a selective circuit associated with each of said means, a collecting cir; cuit common to said plurality of means for receiving currents from the individual selective circuits, and an amplifier having its input coupled to said collecting circuit and 1ts output coupled to said line for amplifying said currents of different frequencies and for impressing them upon said line.

2. Int. signaling system, a transmission line for simultaneously conveying currents of difierent frequencies, terminal apparatus for said line including transmitters of' said frequencies, a common ,ampllfier between said transmitters and said, line, and frequency selective circuits interposed be tween said amplifier and said transmitters.

4. A line for the simultaneous transmission of currents in both directions thereover, a plurality of receiving circuits, 2. plurality of transmitting circuits, a' plurality of sources of current for said transmittingcircuits, means at a terminal station to keep the transmitted currents. out of the local receiving circuits and the received currents out of the transmitting circuits, and an amplifier common to 'a plurality of said-transmitting circuits.

5. In a system of current transmission, a line for simultaneously conveying currents of different frequencies, a plurality of current sources of different frequencies for said line, an amplifier common to said current sources for amplifying said currents of .difi'erentfrequenc-ies and for impressing themupon said line, and means interposed between said amplifier and each of said.

sources for said sources.

6. In a signaling system, a common transmission line, sources of current of ditl'erent frequencies associated with said line, a common unilateral amplifier connected between sa id s0urces and said line, and tuned transmittlng circuits connected between said amplifier and said sources.

preventing interaction among 7. A multiplex signal receiving system comprising a transmission medium, means for amplifying carrier-waves .of difierent frequencies each modulated in accordance with telegraph signals incoming simultaneonsly over said transmission medium, a'selective circuit passing certain of the amplified waves to the exclusion of other waves, a rectifier actuated by current passin throu h said selective circuit, and a trans ating evice energized by rectified 'current from said rectifier.

8. A line for the simultaneous transmission of currents in both directions thereover, a net circuit for balancing the impedance of said line for the transmitted currents, re-

- cuits.

ceiving circuits, transmitting circuits, means for conjugately associating said receivin and transmitting circuits with each other an with said line and net, a plurality of sources of current of different frequencies for said transmitting circuits and an amplifier common to a plurality of said transmitting cir- 9. In a system of current transmission, a transmission medium, a plurality of sources of currents of'different frequencies, a selective circuit associated with each of said sources, a receiving circuit, a net circuit for balancing the electrical characteristics of said medium, means for conjugately associating said receiving and transmitting circuits with each other and withsaid medium and net, and an amplifier common to said selective circuits and said plurality of sources for amplifying said currents of different frequencies and for impressing them upon said conjugate connecting means.

10. In a signaling system, a transmission line, a plurality of individually tuned transmitting circuits associated therewith, a receiving circuit, 'a net circuit for balancing the electrical characteristics of said line for the frequencies corresponding to the individual tuned circuits, means for conjugately associating said receiving and transmitting circuits with each other and with said line and net, and means common to a plurality of said transmitting circuits to prevent reaction between said line and said tuned transmit ting circuits due to the reactive characteristics of said line and said circuits, said ifiiueans comprising a space discharge ampli- 11. A line for the simultaneous transmission of-currents in both directions thereover,

v a plurality of receiving circuits, a plurality of transmitting circuits, a plurality of sources of current for said transmitting circuits, a conjugate arrangement at a terminal station to keep the transmitted currents out of. the localreceiving "circuits and the receiving currents out of the local transmittin circuits and an electron discharge amph er of the push-pull type common to a plurality of said transmitting circuits.

' 12. In a wave transmission system, a transmitting medium, transmltting wave 7 sources of different frequencies, a receiving circuit, a net circuit for balancing the electrical characteristics of said medium, means for conjugately associating said receiving and' transmitting circuits with each other and with said medium and net, and a common means for amplifying simultaneously the waves from said sources and impressing the amplified energies upon said conjugate connecting means, said amplifying means comprising a balanced discharge tube amplifier circuit having a resistance connected across its input terminals, individual selective circuits for said wave sources and.connections from said resistance to said selective circuits in series with one another as a group.

13. In a signaling system, a transmission line, a plurality of individually tuned transmitting circuits associated therewith, and means to prevent reaction between said line and said tuned transmitting circuits due to the reactive characteristics of said line and said circuits, said means comprising an amplifier of the push-pull type.

14. A line for the simultaneous transmission of currents in both directions thereover, a plurality of receiving circuits, a plurality of transmitting circuits, a plurality of sources of currents for said transmitting circuits, means at a terminal station to keep the transmitted currents out of the local receivi'ng circuits and the received currents out of the transmittmg circuits, and an elecsistance connected across its input terminals,

individual selective circuits for said wave sources and connections from said resistance to said selective circuits in series with one another as a group.

In witness whereof, I hereunto subscribe my name this 15th day of May A. D., 1919.

HARALD J. VENNES. 

